When Fenton's reagent (hydrogen peroxide and a ferrous salt) is used in conjunction with a sulfoxide, .alpha.-cleavage of the sulfoxide occurs to produce carbon-centered radicals and a sulfinic acid.
The combination of H.sub.2 O.sub.2 -Fe(II) and dimethyl sulfoxide is one of the most efficient sources of the methyl radical (P. Bruni et al., Proceedings of the 5th International Symposium on Organic Free Radicals; H. Fischer, H. Heimgartner, Eds., Springer-Verlag: Berlin, 1988; p. 73).
The formation of 2-methoxy- 1,1,3,3-tetramethylisoindoline from the reaction of 2-oxyl-1,1,3,3-tetramethylisoindoline with ferrous sulfate, hydrogen peroxide, and dimethyl sulfoxide has been reported (E. Rizzardo et al., Aust. J. Chem. 1982, 35, 2013).